Restraints and Safety Systems: Description and Operation
RESTRAINTSDESCRIPTION
FRONT AIRBAG SYSTEM
A dual front airbag system utilizes driver and passenger airbags. Both the driver and passenger airbags are certified to new federal regulations, which allows them to deploy with less force than prior airbags. The primary occupant restraints in this vehicle are the seat belts, which require active use by the vehicle occupants. The front airbag system is a supplemental passive restraint that was designed and is intended to enhance the protection for the front seat occupants of the vehicle when used in conjunction with the seat belts.
The driver airbag includes an inflatable airbag and an inflator unit behind a trim cover in the hub area of the steering wheel. The passenger airbag includes an inflatable airbag and an inflator unit behind an airbag door in the instrument panel above the glove box.
The dual front airbag system consists of the following components:
- Occupant Restraint Controller (ORC) (4)
- Airbag indicator lamp
- Clockspring (2)
- Knee Blocker Airbag (5)
- Driver and passenger airbags (including the airbag inflators) (1 and 3)
- Wire harness and connections
Refer to the proper Body Diagnostic information to test or diagnose a problem with any component of the front airbag system.
SIDE IMPACT AIRBAG SYSTEM
The Side Impact Airbag System utilizes two airbags, one mounted to each front seat back frame. This system is designed to enhance protection of occupants in the event of a side impact collision. The ORC supports the Satellite Acceleration Sensors (SAS), Seat Airbags, and an accelerometer that provides verification of the direction and severity of an impact from the both sides.
BELT TENSIONER SYSTEM
The seat belt system incorporates Tensioner Modules. They are integral to the seat belt retractors (1) and cannot be serviced. If found defective they must be replaced.
OPERATION
FRONT AIRBAG SYSTEM
The front airbag system electrical circuits are continuously monitored by a microprocessor and software contained within the Occupant Restraint Controller (ORC). The ORC also contains impact sensing elements, which are monitored by the ORC to determine when an impact occurs that is severe enough to require front airbag system protection. When a frontal impact is severe enough, the ORC initiates the inflator units of both front airbags to deploy. An airbag indicator lamp in the instrument cluster lights for six to eight seconds as a bulb test each time the ignition switch is turned to the ON position. Following the bulb test, the airbag indicator lamp is turned ON or OFF by the ORC to indicate the status of the airbag system. If the airbag indicator lamp comes ON at any time other than during the bulb test, it indicates that there is a problem in the airbag system. Such a problem may cause the airbags not to deploy when required, or to deploy when not required.
During a frontal vehicle impact, the knee blockers work in conjunction with properly adjusted seat belts to restrain the driver and front seat passenger in the proper position for an airbag deployment. The knee blockers also work to absorb and distribute the crash energy from the driver and front seat passenger to the structure of the instrument panel. The driver side knee blocker is integral to the lower instrument panel bezel. The passenger side knee blocker is integral to the glove box door. If equipped with a knee blocker airbag, the airbag will inflate in the event of a frontal impact when the ORC determines that the impact is severe enough to fire the second stage of the rest of the front airbags.
SIDE IMPACT AIRBAG SYSTEM
The ORC controls the seat back mounted airbags (one left and one right). If a ORC determines the impact is severe enough, based upon a signal from the Satellite Acceleration Sensor (SAS), the ORC will send a signal and the appropriate airbag will inflate, tearing open the front seat back trim cover protecting the occupants. Once a seat back mounted airbag has been deployed, the entire seat back as well as any damaged parts must be replaced.
BELT TENSIONER SYSTEM
At the onset of an impact event, each tensioner uses a pyrotechnic device which is triggered simultaneously with the airbags to rapidly retract the seat belts. With the slack removed, the occupant's forward motion in an impact will be reduced as will the likelihood of contacting interior components.
WARNING: WHEN THE FRONT AIRBAG IS DEPLOYED, THE TENSIONER WILL HAVE DEPLOYED ALSO, AND MUST BE REPLACED.
The ORC monitors the seat belt tensioner circuit and reports active and stored Diagnostic Trouble Codes (DTC's) if any problem is found.
Once a vehicle has been in an accident, the tensioner will have a Gravel/Grinding sound to it after the tensioner has been put into use. This must be replaced along with any deployed airbags and broken or damaged parts.